J . Am. Chem. SOC.1988, 110, 7249-7250
Siastatin B, a Potent Neuraminidase Inhibitor: The Total Synthesis and Absolute Configuration
7249
Chart I HO
Yoshio Nishimura,* Wen-mei Wang, Shinichi Kondo, Takaaki Aoyagi, and Hamao Umezawa
Institute of Microbial Chemistry 3-14-23 Kamiosaki, Shinagawa-ku. Tokyo 141, Japan Received May 27, 1988
SiastatinB(1)
Neuraminidase (sialidase, N-acetylneuraminate glycohydrolase EC 3.2.1.18),l widely distributed among animal tissues and microorganisms, is involved in various biological functions such as immune response,2 oncogene~is,~ metastasis of tumors," sperm Scheme I" penetration,s and viral infection,6 etc. Siastatin B, a potent inhibitor of neuraminidase, was isolated by Umezawa et aL7 in 1974 from a Streptomyces culture. Siastatin B inhibits neuraminidases isolated from various miL-Ribose croorganisms, animal tissues, and viruses as well as @-glucuronidase and N-acetyl-B-D-glucosaminidase.The relative configuration of siastatin B was determined as 2(S/R)-acetamido-3(S/R),4(R/S)-dihydroxypiperidine-5(R/S)-carboxylic acid by 'H N M R and X-ray crystallographic ~ t u d i e s .However, ~ its absolute configuration was unresolved. We speculated from its biological activity that the absolute configuration of siastatin B should be that shown in 1 by analogy with N-acetylneuraminic acid (2). Here we wish to report the first total syntheses of siastatin B (1) and its enantiomer (3) based on a chiron strategy. Compound 1 has an unusual structure posessing the continuous -CH(NHAc)-NH-CH2-CH(CO0H)constituent in a framework. It is distinct from glycohydrolase inhibitors belonging to the sugar analogues having a piperidine ring such as nojirimycin,* galactostatin: and their congeners.1° Our key intermediate for the synthesis of 1 was lactam 6. The synthesis of 6 began with L-ribose which was transformed to 5-azido-5-deoxy-2,3-0-isopropylidene-L-ribonolactone (5), [aIZZo -16.2' (CHC13), by protection of the 2,3-diol, azide formation, and oxidation" (Scheme I). Hydrogenation of the amide group of 5 and ring expansioni2 afforded crystalline 6 , [ a I z 2 D -16.4' (CHC13), mp 138-140 'C, in good yield. Stereospecific introduction of the hydroxyl group at C(2) was best achieved by hydride reduction of the protected lactam 7 to 8, [alZzD +21' (CHC13), mp 164 'C, and Swern oxidationI3 to give aminal 9, [fxI2*D +11' (CHCIJ, mp 106-107
H
C
O
O
H
OH
N-Acetylneuraminic acid ( 2 )
R'O
R2
N3
~6 R'-R2-H
5
9
c;: $
(1) Gottshalk, K. The Chemistry and Biology of Sialic Acid and Related Substances; Cambridge University Press: London, 1960;pp 75-87. Roseman, S.Chem. Phys. Lipids 1970,5, 270. (2)Simons, R. L.; Rios, A. J . Immunol. 1973,111, 1820. Rott, R.;Becht, H.; Orlich, M. J. Gen. Virol. 1974,22,35. (3) Bekesi, J. G.; St-Arneault, G.; Holland, J. F. Cancer Res. 1971,31, 2130. Bernacki, R. J. Science (Washington, D.C.) 1W7, 195, 577. (4)Gasic, G.; Gasic, T. Proc. N a f . Acad. Sci. U.S.A. 1962, 48, 1172. Yogeeswaran, G.; Salk, P. L. Science (Washington, D.C.) 1981,212, 1514. Dennis, J.; Waller, C.; Timpl, R.; Schirrmacher, V. Nature (London) 1982, 300,274. Fogel, M.; Altevogt, P.; Schirnnacher, V. J. Exp. Med. 1983,157,
AcNH o U
12
= NPht , R 4 = TBDMS
= NHAc.
R4 = H OH
14
13
L
J
16
15
371. ( 5 ) Soupart, P. S.;Clewe, T. H. Ferf. Sferil. 1965,16,677.
(6)Ackermann, W.W.;Ishida, N.; Massab, H. F. J. Exptl. Med. 1955, 102,545. Haff, R. F.; Stewart, R. C. J. Immunol. 1965,94, 842. Lipkind, M. A.; Tsvetkova, I. V. Arch. Ges. Virusforsch. 1970,29, 370. Huang, R. T. C.; Rott, R.; Wahn, K.; Klenk, H. D.; Kohama, T. yirology 1980,107,313. (7) Umezawa, H.; Aoyagi, T.; Komiyama, T.; Morishima, H.; Hamada, M.; Takeuchi, T. J . Antibiof. 1974,27, 963. (8)Inouye, S.; Tsuruoka, T.; Niida, T.J . Anfibiof.1966,Ser. A19, 288. (9)Miyake, Y.; Ebata, M. J . Anfibiof.1987,40, 122. (10) Inouye, S.;Tsuruoka, T.; Ito, T.; Niida, T. Tetrahedron 1968,23, 2125. Schmidt, D. D.; Frommer, W.; Muller, L.; Truscheit, E. Natunvissenschaften 1979,66,584. Fleet, G. W. J.; Smith, W.; Evans, S. V.;Fellows, L. E. J . Chem. SOC.,Chem. Commun. 1984,1240. Fellows, L.E.; Bell, E. A.; Lynn, D. G.; Pilkiewicz, F.; Nakanishi, K. J . Chem. Soc., Chem. Commun. 1979,977. (11) Hanessian, S.J . Org. Chem. 1969,34,675. (12) For a review, see: Paulsen, H.; T d t , K. In Advances in Carbohydrate Chemistry: Cyclic Monosaccharides Having Nitrogen or Sulfiur in fhe Ring Wolfrom, M. L., Tipson, R. T., Eds.; Academic Press: New York, 1968;Vol. 23, pp 115-232. (13)Mancuso, A. J.; Huang, S.-L.; Swern, D. J. Org. Chem. 1978,43, 2480.
0002-7863/88/1510-7249$01.50/0
17
'(a) p-TsOH, Me,CO; CH3SOzCI, C6HsN; NaN,, DMSO; CrO,/ C ~ H S N CHZCl2, , 89%; (b) H,, Raney Ni, MeOH, 88%; (c) f BuMe2SiC1, imidazole, DMF; PhCH20COCI, NaH, DMF, 99%; (d) NaBH4, EtOH, 70%; (e) (COC1)2, DMSO, Et3N, CH,CI,, 88%; (f) phthalimide, Ph3P, DEAD, DMF, 100%; (g) NHzNH2, MeOH; AczO, C6HjN; n-Bu4NF, THF, 100%; (h) Ru04, CH,C12/CC14, 99%; (i) CH3N02, NaH, DME, 100%; 6 ) p-TsOH, A c ~ O ;K2CO3, C6H6,100%; (k) C6HSN, 38 OC, 80%; (I) CH3CH=C(CH3),/r-BuOH, NaOCI,NaH,PO,/H,O; MEMCI, (i-Pr),NEt, CH,C12, 55%; (m) NaBH,, 1:lO CF3CH20H/THF, 75%; (n) PDC, DMF; H2, 5% Pd/C, MeOH; 1 M aqueous HCI, then Dowex 50W-X4(H' form) eluted with NH4OH, 66%.
'C. The 'H N M R spectrum of 9 shows a proton of C(2) at 6 5.55 (a singlet with a small coupling, J < 2 Hz), clearly indicative of an equatorial hydrogen. Strikingly a single stereoisomer 0 1988 American Chemical Society
7250
J . Am. Chem. Soc 1988, 110, 7250-7252
controlled by an anomeric effectI4 results from this oxidation, whereas oxidation with CrO, in pyridine gives a 2:l mixture of 9 and its epimer at C(2). Displacement of the axial hydroxyl group to the equatorial amino group proved troublesome until we discovered that the Mitsunobu reaction15 (PPh3, diethyl azodicarboxylate, phthalimide) in N,N-dimethylformamide gave the desired product 10, +26.4’ (CHCI,), mp 109 ‘C (dec), quantitatively. The stereochemistry at C(2) was established by its H N M R spectrum which shows a proton of C(2) at 6 5.91 (d, J = 5 Hz), clearly indicative of an axial hydrogen. Replacement of the amino substituent and removal of the tert-butyldimethylsilyl group to 11, [.]22D -20.4’ (CHCIJ, and oxidation -56’ (CHCI,), were unexceptional. to 12, [.]”D Condensation of 12 with nitromethane was found to proceed smoothly to give 13 as a single stereoisomer, [.IUD +26’ (CHCl,), quantitatively. The Stereochemistry at C(5) is tentatively assigned as 13. Acetylation of 13 followed by base-catalyzed elimination +69’ (CHC13), in a good of the acetoxy group afforded 14, [.I2’D yield. The structure of 14 was determined by its I H N M R spectrum which shows the methylene protons of the nitromethyl group at 6 4.78 and 5.16 (ABq, J = 15 Hz), a proton of C(4) at 6 4.71 (d, J = 6 Hz), and a proton of C(6) at 6 7.06 (S). Transformation of 14 to carboxylate 16, [ctI2’D -4.1’ (MeOH), mp 194-198 ‘C (dec), was achieved via a,@-unsaturated aldehyde 15 produced by simply warming 14 in pyridine. Compound 16 was also successfully produced from 13 by the stepwise successive sequences without isolation. A problem arose, however, as catalytic reductionI6 of 16 accompanied by elimination of the hydroxyl group at C(4) and hydride reduction1’ of the double bond proceeded unfavorably and without chemoselectivity. To circumvent this problem, 16 was stereoselectively hydrogenated to .,@-saturated hydroxymethyl compound 17 (NaBH4, 1:lO CF3CH20H/THF), [.]22D +7.0° (CHCI,). The IH N M R spectrum of 17 shows protons at 6 3.25 (t, J = 13 Hz, H-6 ax), 3.59 (dd, J = 5 and 13 Hz, H-6 eq), and 4.54 (dd, J = 3 and 8 Hz, H-4), clearly indicative of an axial hydrogen at C(5). The remaining steps of the synthesis are rather straightforward. The carboxylic acid formed upon oxidation of 17 was converted +56’ by removal of protecting groups to crystalline 1, [.]*’D ( H 2 0 ) (lit.’ 57.2’ (H20)), mp 135-136 ‘C (dec) (lit.’ 137 ‘C), in 10.3% overall yield from L-ribose. Its spectral properties (IR, ‘H NMR, I3C NMR, mass spectrum) were superimposable with those of the natural specimen. The enantiomer 3 was also synthesized from D-ribonolactam by the same method used in the synthesis of 1. Compound 3 was identical in all respects with the synthetic and the natural 1 except for the sign of the specific rotation. Thus, the absolute configuration of siastatin B has been elucidated as the (2R,3R,4S,SS)-isomer 1. The synthetic 1 shows the same inhibitory effects as the natural one against neuraminidases prepared from CI. perfringens, Streptomyces, rat mammary gland, rat mammary liver, chorioallantoic membrane (IC50 = 3, 10, 110, 170 and 55 pg/0.5 mL, respectively), @-glucuronidase(IC50 = 4 pg/0.5 mL), and Nacetyl-@-D-glucosaminidase(IC; = 18 pg/0.5 mL).’ In contrast, compound 3 shows only weak activities against neuraminidases mentioned above (ICso: more than 100 p g / 0 . 5 mL), whereas 3 demonstrates activity against &glucuronidase (IC, = 25 pg/0.5 mL). (14) Lemieux, R. U.; Kulling, R. K.; Bernstein, H. J.; Schneider, W. G. J . Am. Chem. SOC.1958, 80, 6098. (15) For a review, see: Mitsunobu, 0. Synthesis 1981, 1. (16) Hanessian, S.; Lavallee, P. Can. J . Chem. 1977.55, 562. Anderson, R. C.; Fraser-Reid, B. Tetrahedron Letf. 1978, 3233. Hanessian, S.; Rancourt, G.; Guindon, Y. Can. J . Chem. 1978,56, 1843. Corey, E. J.; Goto, G. Tetrahedron Lett. 1980, 3463. (17) Kadin, S. B. J . Org. Chem. 1966, 31, 620. Satoh, T.; Nanba, K.; Suzuki, S. Chem. Pharm. Bull. 1971,19,817. Ganem, B.; Fortunato, J. M. J . Org. Chem. 1975, 40, 2846. Hutchins, R. 0.;Rotstein, D.; Natale, N.; Fanelli, J. J . Org. Chem. 1976, 41, 3328. Kumar, Y.; Florvall, L. Synth. Commun. 1983,13,489. Setoi, H.; Takeno, H.; Hashimoto, M. J . Org. Chem. 1985, 50, 3948.
0002-7863/88/1510-7250$01.50/0
Observation and Substituent Control of Medium-Dependent Hot-Molecule Reactions in Low-Temperature Matrices Brian F. LeBlanc and Robert S. Sheridan**’ Department of Chemistry, University of Nevada Reno, Nevada 89557 Received April 4, 1988 Although reaction from vibrationally excited products is common in the gas phase, hot-molecule chemistry in condensed phases is rare.’ Vibrational energy transfer to the medium is generally faster than chemically activated reaction. There are, however, a handful of cases where hot-molecule reactions of ground-state products of therma13-5 or photochemica16-8 processes in various media have been proposed to explain unexpected products. Reaction from upper vibrational levels in electronic excited states has also been suggested in several instances%” to rationalize wavelength dependence in condensed phase photochemistry. There is spectroscopic evidence that vibrational relaxation in inert-gas matrices may be slow relative to solution. For example, Bondybey12 and R e n t z e p i ~ have ’ ~ observed relatively long-lived hot bands (ca. 300 ps) in the fluorescence spectra of various aromatics in rare-gas matrices at 4 K . The higher energy vibrational emissions are absent in hydrocarbon mat rice^'^ or when the substrates are methylated.lZb The surprising lifetimes have been attributed to mismatch of the vibrations of the aromatics and the low-energy lattice modes of the matrices, leading to poor energy transfer.”.13 IR induced conformational interconversions in matrices are also well known.5 The possibility of slow vibrational relaxation of photoproducts raises concerns for the observation of highly reactive intermediates with matrix-isolation techniques. We now wish to report chemical evidence, based on media and substituent effects, for the formation of vibrationally hot photoproducts in low-temperature matrices and their subsequent ground-state reactions. We have reported that irradiation of 1 in toluene-d8 at 77 K gives primarily 7-norbornadienone (2), characterized by ’ H N M R at -78’ C.15v’6 A minor product, tentatively assigned as 3, was also observed. On warming to ca. -60 ‘C, 2 cleanly gave benzene (and CO), with AG* = 15 kcal/mol. Side product 3 polymerized
(1) Fellow of the Alfred P. Sloan Foundation, 1986-1988. (2) Bondybey, V. E. Ann. Reu. Phys. Chem. 1984, 35,591 and references
cited therein. (3) Farneth, W. E.; D’Amore, M. B.; Brauman, J. I . J . Am. Chem. SOC. 1976, 98, 5 546. (4) Rohman, M.; Shevlin, P. Tetrahedron Lett. 1985, 26, 2959. (5) Frei, H.; Pimentel, G. C. Ann. Reo. Phys. Chem. 1985, 36, 491 and
references therein. (6) Teki, Y . ; Takui, R.; Itoh, K.; Iwamura, H.; Kobaayashi, K. J . Am. Chem. SOC.1986. 108. 2147. (7) Jain, R.; McElwee-White, L.; Dougherty, D. A. J . Am. Chem. SOC. 1988, 110, 552. (8) Vibrational lifetimes in diatomics can be extremely long in condensed
phases? and this can play a role in their chemistry. See, for example: Smith, D. E.; Harris, C. B. J . Chem. Phys. 1987,87, 2709. (9) (a) Castellan, A,; Kolc, J.; Michl, J. J . Am. Chem. SOC.1978, 100, 6687. (b) Souto, M. A.; Kolc, J.; Michl, J. J . Am. Chem. SOC.1978, 100, 6692.
(IO) Mauring, L. E.; Peters, K. S. J . Am. Chem. SOC.1984, 106, 8077. ( I 1) Barbara, P. F.; Brus, L. E.; Rentzepis, P. M. J . Am. Chem. Soc. 1980, 102, 5631. (12) (a) Huppert, D.; Bondybey, V. E.; Rentzepis, P. M. J . Phys. Chem. 1985,89,5811. (b) Bondybey, V. E.; Haddon, R. C.; Rentzepis, P. M. J . Am. Chem. Soc. 1984, 106, 5969. (c) Rentzepis, P. M.; Bondybey, V. E. J , Chem. Phys. 1984,80,4127. (13) (a) Hopkins, J. B.; Rentzepis, P. M. Chem. Phys. Lert. 1985, 117, 414. (b) Hopkins, J. B.; Rentzepis, P. M. Chem. Phys. Lett. 1987, 142, 503. (c) Huppert, D.; Rentzepis, P. M. J . Chem. Phys. 1987, 86, 603. (14) Gillispie, G. D. J . Chem. Phys. 1985, 85, 4825. (15) LeBlanc, B. F.; Sheridan, R. S. J . Am. Chem. SOC.1985, 107, 4554. (16) For an alternate synthesis and investigation of 7-norbornadienone,see: Birney, D. M.; Berson, J. A. J . Am. Chem. SOC.1985, 107,4553. Birney, D. M.; Berson, J. A. Tetrahedron 1986, 43, 1561.
0 1988 American Chemical Society
